I wonder which is the best way to transition from an open beta to a closed product behind a paywall, especially towards people who are already using the app...
an email warning them a couple of weeks in advance?
an email with immediate effect?
don't charge at all to current users and add a paywall for the new ones? <--- of course this is the nicest one, but my goal here is to actually validate the product, so I wonder if any of all the users who have been using the app daily would be willing to pay..